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Hi all,
I am currently attempting to create a network of interlocking curves that I can convert to a surface. Id like to effectively use the curves as a guide to create a nurbs surface.
The problem I am facing is in areas where more than 2 curves meet any form of skinning seems to fail me.
What would be the best method to create a surface between each of these curves?
Thanks for your time guys!
CurvesProblem.hip

Hello! First time posting. I'm new to Houdini, this is my first project that I decided to do. But I'm a fairly seasoned C4D 3D generalist so I know what I want to do in Houdini, I just don't know how to go about it.
I'm in Houdini 17.5. Here is the problem. I have stumbled around in Houdini and made a Viscous Flip Fluid Sim. I made a Sphere an emitter, and emitted my fluid pouring onto a .OBJ mesh that I imported in. I've cached the particle FLIP Particle simin the DOP network, the Particle Fluid Compressed Cached, and Particle Fluid Surface Cached.
Now here is my problem. I exported my meshed sim as an alembic from a ROP_Alembic node. Imported into C4D. And then I realized I have a UV problem.
This is a Redshift texture and shading pass that I did with my sequence. At the time I forgot to plug in the velocity data tags from the Alembic sequence into the Redshift motion vector blur, so if it looks weird, that is why.
Crystal_Goo_Test.mov
My texture smudges are on the mesh, but they stay static while the mesh animates. It looks just like the textures from this cartoon it doesn't move with it.
So after a bit of digging I realize I don't even have UV's. Because Flip Fluids don't come with UV's, and if I never defined any UV's then how could they just magically appear? lol. So I tried researching how to generate them, and how to export them with the alembic. But for my specific situation I couldn't find anything that was up to date and worked. OR I am too much of a noob to implement what I saw in forum posts. The stuff I saw was for Houdini version 13, 14.5 and 16. I'm on 17.5.
Here is a screen shot of how I tried to generate UV's and export them, again I never re-cached my sim yet. I just tried to put uv's on my existing set up.
Below is my emitter. And there are no UV's on this sphere primitive, nor anywhere before the output. I took a shot in the dark and tried to see if I could generate them after all my caches (because it took 3 days to cache the fluid surface mesh). So I honestly have no idea where to generate these uv's, how to do it correctly, and how to get them passed onto the fluid mesh for alembic export and texturing in C4D Redshift.
I'm including my .hip file with my cache's disconnected. They are over 200 GB's all together so it's too big to include here. Lower the substeps in the Flip Solver or lessen the Fluid Mesher to make it play back faster. I used high settings for my final export (also I tried my best to optimize, but again I'm a noob with Houdini and have probably done things incorrectly in my set up). Crystal_Viscous_Sim.zip
The FLIP DOP cache might still need to be disconnected.
This is the final step of my personal project. I've done all this on my own but I'm super stuck on this UV generation and export. And once I can export this fluid mesh an an alembic sequence for C4D Redshift I will be set to render.
Thank you in advance for any feedback and/or answers. Please write out instructions very clearly for me to replicate if you don't want to provide pictures/ screenshots or .hip files.
Again what I'm trying to do is generate UV's for my Fluid Surface, and have then be able to be exported via an Alembic sequence for texturing and rendering in Redshift.

Hi, please see the attached Cinema 4D video of what I am trying to replicate in Houdini.
I want to interactively position an object on a surface using handles.
I made some progress with the Creep SOP, but it has several limitations:
it deforms the source object, which I don't want
it doesn't have viewport handles, so I have to edit the node parameters, which is undesirable (I have a lot of objects to manually position, so I want to make it as easy as possible)
it doesn't work with polygonal objects
I don't mind using VEX or an Attribute VOP to achieve this.
Thanks.
Slide_on_Surface.mp4

Hi folks, I'm a games artist and am new to Houdini and I'm looking for a bit of workflow advice for an effect I'm trying to achieve.
I'm wanting to make a melting head. I've got a UV'd head and I've put a skull mesh underneath that will be revealed.
I've added a viscous fluid melt operator and the head melts and drips nicely. I would like to put it into UE4 as a realtime effect. The issue I'm having is that the melt mesh has changing topology and I need stable UV's so that I can apply my head texture to it.
Is there a way to do this, either by taking the UV's at the first frame of the sim or by point deforming my undistorted head mesh to the simmed mesh. Or should I consider another way of achieving this effect? Any thoughts would be appreciated. Cheers, Paul

Hello!
I would like to recreate the following effect:
LiquidSurface.mp4.mp4
I want to apply an image texture (with normal, bump, roughness, ... maps) to a plane that deforms in the certain way that it does in the .mp4 that i attached as a file. Do you guys know the technique behind this?

I have quite a simple question but haven't been able to figure it out yet. Using attribfrommap I have particles getting generated from a texture (e.g. circle). How can I attract/morph these particles to another texture (e.g. rectangle)?
Thanks

Hello!
I'm working on a custom toon shader. As a basis I want to use the lambert lighting model as described in the tutorial embedded below. To test this I created a very simple scene with a sphere placed at the origin, a point light and a material with the material builder applied to the sphere (see image below).
Now, here's the problem: The shading of the sphere is incorrect as soon as the point light has negative coordinates. It seems as if the surface_global's P and N are expressed in a different space compared to the point light's position. This happend with Mantra as well as Redshift (where I used the same setup as in the video below, apart from getting the light's position through a constant and channel references). Am I wrong to assume that P is the world position of the current point being shaded and N is it's normalised normal? Is this the wrong way to get the light position into the shader? I spent some time testing and searching on the internet but I couldn't find anything that clarified these quesitons sufficiently for me.
custom_lambert.hipnc

I am trying to get a calm puddle, and I have managed to achieve that in most of the fluid.
Still, I can't get rid of this moving particles at the boundaries.... I've tried deleting them, but new ones will start moving until they get there...
puddle_02.mov

Hey!
Could someone help me understand this? I have noise going into the vector displacement of a principled shader. Why do I have change the amplitude of the noise in z-axis to affect the y (up/down) position? If I do the same at sop level I can just adjust the amplitude in the y value. I tried messing around with the transform vop, but I didn't get anything working.
Thanks
displace.hiplc

Hello,
The title may be not that clear so rather then tell, I will show what I need to achieve first and then I will describe my approach (or better say approacheS, because I have been banging my head against the wall for quite some time with this). So basically here is what I need (did this quick and dirty animation in C4D): https://www.dropbox.com/home?preview=test.mp4
Now the tricky part is that this animation has to loop.
Initially I started in C4D. Made some particles crawling along the surface of the statue, cloned some primitives on those particles and applied dynamics. It all works great but how do I loop it.
Simulations are are very tricky to loop (especially in C4D) so I decided to go the Houdini way and try to build procedural setup that would give me similar result. My initial thoughts of the setup are the following:
- scatter points on statue
- make them move with the noise and use (minpos() function to stick them to the surface), and use periodic noise so the movement can be easily looped.
- every frame attribute transfer normals of the statue to the moving points, so that when I copy objects they will be aligned to the surface
- copy objects onto points and make sure there transformation axis is at the bottom so that when copied they appear on the surface of the statue
- check for intersections with the statue (still not sure how to approach it but as far as I remember there is a way to see if two meshes intersect or not
- if they intersect, move the object away from the statue along the normal of the point it is copied onto (I think this will have to be done in solver so that I move it slightly and then check for intersections again, because the distance the object has to be moved may differ)
- I still do not know how to avoid intersection between all the objects on the statue themselves ( do not have any ideas so far)
For now I am stuck on trying to loop the movement of the points. I can loop them easily in 3D space but when I minpos() them on to the surface they jump from time to time. I understand why this happens but can't figure out how to avoid it. I tried attrib transfering the normals of the statue to the points every frame (in solver) and then calculating the cross product between normal of the point and vector generated bu the noise. This gives pretty smooth movement but the loop breaks of course as you may have guessed.
Anyway, thanks for reading this far. If you have any ideas on how to make it work, please let me know, I appreciate any input. I have posted same question on the SideFx Forums on friday but it is still been reviewed (takes so long). Maybe I am overthinking things and there is easier way to do it say in C4D, in case you know it, please let me know. And do you think my thinking process is somewhat right?
Looking forward to any help.
Have a great day everyone!

Hi guys, I've already posted this on FB group with no answear so you're my last hope.
I have a problem with normals demonstrated in the video, basically object animated on a curve and aligned to the curves tangents hits a geo and gets stuck in it but it doesn't rotate along with it. So basically the question is how can i match the movement of normals of the object beign hit and hitting so that it rotates properly?
Here is simplified .hip: link

Hi,
I'm creating water simulation via "Guided Ocean Layer". My problem is in surface of the simulation. I need to keep surface the same or close to the first frame all the time of simulation. The pattern of the simulation is from Ocean spectrum and wavetank. The problem is that through the time of simulation the surface loses quality. Pictures listed below.
Are there any options how to keep the quality of the surface in DOP of simulation?
Thank you for your advices.
Vojta

Hi everyone.
Does anybody know how to use surface field in voppop or some dopvop to find the distance between my particles and surface. I want to make a force wind that depends on distance between surface and particles, so the farther point from the surface, the stronger the force of the wind. And the surface has really big waves for example, thats why i cant use just P.y for power of force for flat surface. Hope I explained it clearly)

Hi all,
Does anyone know how to use the mask input option to smooth a part of the mesh inside the particle fluid surface node?
I want to specify with a volume (ie. a bounding box) which part of the mesh to smooth or keep (instead of using the velocity or vorticity mask).
I created the volume to mask with (just a box turned to vdb) as a separate OBJ, I am then object merging it and connecting it to the third input of the fluid surface node, then in the filtering tab in mask input I check it and put in the name of the volume. I have tried to do several different things on the volume itself (regular VDB, Fog VFB, etc.) and nothing seems to work or make any difference. When I turn visualize mask on all it shows is nothing is applied to it (ie. all of the surface has 0 smoothing applied to it)
How do I properly use this feature and get the node to recognize the mask? Am I going about this the right way?
Many thanks,
CrownSplash Anim C.hiplc

Hello!
I can't get to work the new ocean surface setup, even with the provided scene files. I the viewport it's seems fine, but it renders flat. (and without the foam)
Yes, I baked the spectra node.
Can anyone point me in the right direction? There is none learning material about the new ocean surface, not a single tutorial, only the masterclass.
Thanks

Hi all
I have a question about exporting geometry using .fbx - Basically I want to export certain model that has been created in Houdini and render it in Keyshot, while in Houdini the model looks smoothed as shown in the pic attached sc_from_houdini.png but when i import it in Keyshot it comes totally black opaque and unable to receive new materials. I can overcome this situation by entering dummy (zero) changes to the geometry in Keyshot, which renders it able to receive materials and be rendered properly.
Now, the problem I find is that once this first issue is fixed, the result of the render is showing the raw polygons and not a smooth surface as it appeared in the Houdini renders, as we can see on sc_from_keyshot.png attached.
Anyone have idea what this happens? Perhaps I am missing some step before exporting the geometry, or exporting it wrongly?
Sorry is not the same exact camera, but is the exact same geometry, I also attach here the houdini .fbx exported file )
Thanks in advance )
s.fbx

Hello community,
I'm trying to figure out how to get this effect, im pretty new to houdini and my thoughts are with some noise and displace along normals, I played a lot with vopsd and solver but I cant get the shapes and amount of detail, could this detail be done in mantra? (just wondering, I would prefer to do it just in sops)
Here is the video (min 7:39)
Any tip on how to achieve this kind of pattern/displace will be great, thanks!

hi,
I try to work with the relbbox node in a shader just like in sops but it doesnt give me the desired results. The picture below shows my network in the shader which I thought should give me a gradiant from bottom to the top of the box. But it looks like that I´m missing something.
I read that P in shading context is P in camera space. But converting it from cam to obj space also didn´t change anything. I would be thankfull for some help here.

Hey guys,
Anybody knows how can I get this effect? maybe with attribute transfer? I tried doing a plane with 10-1, resample, unroll, then tried to deform the body with ray sop and with attribute transfer with no luck.
Maybe with particles that flows until touchs the surface and then continue?, I also tried doing a bunch of planes with a cookie sop but I get a mess.
I'm also attaching 2 more samples that are similar, I'm more interested in the girl body one, I dont know why but I have the feeling that an attribute transfer may be the way to control at least the face, but im newbie.
Thanks!

Hello,
is there a VEX function for sampling N at arbitrary location in NURBS surface (based on uv location for example)?
One way would be to convert NURBS to polys and get normals from them. But I thought that maybe there is easy way of getting N directly from NURBS?
Thanks,
Juraj

Hi,
I have been trying to deform scatter point over the surface of the geometry,
What would be the way to deform or slide scatter or give slide scatter points with offset over time on the surface of the geometry ?
I have tried with color texture and it worked, but i am looking forward for the VOP method,
can someone guide me over that ?
I am still to houdini and trying things out.
Thank you,

Guys! Need your help!
I stock....
Here is my issue.
I have some particles that when impact with the surface (grid for example) create attr (marked as red for example).
My task is grow this attribute by the time on surface in differnt directoins.
I understand that effect can be achive by using SOP Solver, but can't understand for now how to do this.
Explaning about how to make that happen will be highly appreciated!
I attach hipnc file with my problem.
Thank you advance guys!
growing_attr_002.hipnc

Hello,
I'm trying to control some particles, I need them to travel on a ground, toward an object, then creep up on that object surface, when they reach it.
I've tried a few method (creep, ray, slide on collision ...) but even if I manage to have them slide on an object surface, my problem is how to set up the POP network in order to have them transitioning from one surface to another.
I've cheated with a P.y = 0 in order to have them on the ground with ease, but I'm failing at controlling a nice transition from ground to object.
here is a basic setup, without much, in order to not restrict the different approaches .
Also, I'll replace the particle with a small disk later, so I think I need them (particles) to be oriented properly.
Thanks for any advise and help!
prtcl_slide_4OD.hipnc

Hello guys!
I'm some kind of a newbie to Houdini but not really in the 3D field.
I would like to have some feedback and your opinion on my ocean shader. It's a simple scene which will be animated with a camera traveling toward the horizon, I use it to learn more about houdini ocean shader.
Here's my shot :
It's been few days I'm struggling with this one, so any feedback is more than welcome! Thank you guys, have a nice day.